System Integration Unit

For more information on alternate functions, refer to the Source Unit column in Table 4-1for the appropriate section of this document.

Table 4-1. GPIO Alternate Functions (Sheet 1 of 4)

Pin

Alternate

Alternate Function

AF{n}

Source Unit

Signal Description and comments

Function Name

Assignment

encoding

 

 

 

 

 

 

 

 

 

GP1

GP_RST

ALT_FN_1_IN

01

Clocks & Power

Active low GP_reset

Manager Unit

 

 

 

 

 

 

 

 

 

 

 

GP6

MMCCLK

ALT_FN_1_OUT

01

Multimedia Card

MMC Clock

(MMC) Controller

 

 

 

 

 

 

 

 

 

 

 

GP7

48 MHz clock

ALT_FN_1_OUT

01

Clocks & Power

48 MHz clock output

 

 

 

 

Manager Unit

 

GP8

MMCCS0

ALT_FN_1_OUT

01

Multimedia Card

MMC Chip Select 0

GP9

MMCCS1

ALT_FN_1_OUT

01

(MMC) Controller

MMC Chip Select 1

 

 

 

 

 

 

 

GP10

RTCCLK

ALT_FN_1_OUT

01

System Integation

real time clock (1 Hz)

Unit

 

 

 

 

 

 

 

 

 

 

 

GP11

3.6 MHz

ALT_FN_1_OUT

01

Clocks & Power

3.6 MHz oscillator out

GP12

32 kHz

ALT_FN_1_OUT

01

Manager Unit

32 kHz out

 

 

 

 

 

 

 

GP13

MBGNT

ALT_FN_2_OUT

10

 

memory controller grant

 

 

 

 

 

 

GP14

MBREQ

ALT_FN_1_IN

01

 

memory controller alternate bus

 

master request

 

 

 

 

 

 

 

 

 

 

 

GP15

nCS_1

ALT_FN_2_OUT

10

 

Active low chip select 1

 

 

 

 

 

 

GP16

PWM0

ALT_FN_2_OUT

10

 

PWM0 output

 

 

 

 

 

 

GP17

PWM1

ALT_FN_2_OUT

10

 

PWM1 output

 

 

 

 

Memory Controller

 

GP18

RDY

ALT_FN_1_IN

01

Ext. Bus Ready

 

 

 

 

 

 

 

GP19

DREQ[1]

ALT_FN_1_IN

01

 

External DMA Request

 

 

 

 

 

 

GP20

DREQ[0]

ALT_FN_1_IN

01

 

External DMA Request

 

 

 

 

 

 

GP23

SCLK

ALT_FN_2_OUT

10

 

SSP clock

 

 

 

 

 

 

GP24

SFRM

ALT_FN_2_OUT

10

 

SSP Frame

 

 

 

 

 

 

GP25

TXD

ALT_FN_2_OUT

10

SSP Serial Port

SSP transmit

 

 

 

 

 

 

GP26

RXD

ALT_FN_1_IN

01

 

SSP receive

 

 

 

 

 

 

GP27

EXTCLK

ALT_FN_1_IN

01

 

SSP ext_clk

 

 

 

 

 

 

 

BITCLK

ALT_FN_1_IN

01

AC97 Controller Unit

AC97 bit_clk

 

 

 

 

 

 

GP28

BITCLK

ALT_FN_2_IN

10

I2S Controller

I2S bit_clk

 

 

 

 

 

 

BITCLK

ALT_FN_1_OUT

01

I2S bit_clk

 

 

 

 

 

 

 

 

GP29

SDATA_IN0

ALT_FN_1_IN

01

AC97 Controller Unit

AC97 Sdata_in0

 

 

 

 

 

SDATA_IN

ALT_FN_2_IN

10

I2S Controller

I2S Sdata_in

 

 

 

 

 

 

 

GP30

SDATA_OUT

ALT_FN_1_OUT

01

I2S Controller

I2S Sdata_out

 

 

 

 

 

SDATA_OUT

ALT_FN_2_OUT

10

AC97 Controller Unit

AC97 Sdata_out

 

 

 

 

 

 

 

GP31

SYNC

ALT_FN_1_OUT

01

I2S Controller

I2S sync

 

 

 

 

 

SYNC

ALT_FN_2_OUT

10

AC97 Controller Unit

AC97 sync

 

 

 

 

 

 

 

GP32

SDATA_IN1

ALT_FN_1_IN

01

AC97 Controller Unit

AC97 Sdata_in1

 

 

 

 

 

SYSCLK

ALT_FN_1_OUT

01

I2S Controller

I2S System Clock

 

 

 

 

 

 

 

Intel® PXA255 Processor Developer’s Manual

4-3

Page 107
Image 107
Intel PXA255 manual Gpio Alternate Functions Sheet 1